This invention relates to an environmental hood assembly for capturing contaminating fumes, dust and the like, and more particularly to an adjustable hood assembly for capturing and collecting dust and other particulate material released during the filling of a container with dry material such as cement, aggregate, or similiar materials.
In the typical batch cement plant for producing cement for construction and other purposes, individual transit mix trucks are generally filled with a dry mix of cement and other appropriate aggregate materials from a batch plant through a hopper or series of hoppers which introduce the material into the truck mixer drum through a chute directed into the mouth of the mixer drum. Water for completing the mix is generally stored in a tank on the truck and introduced during the mixing operation after the dry materials have been deposited into the mixer drum. Even when the dry materials are introduced simultaneously with water, there is still a significant amount of airborne dust and particulate matter created in this filling operation. As environmental regulations concerning air pollution and the like have become increasingly restrictive, cement plants must be able to prevent the release of dust and other particulate matter into the surrounding atmosphere during truck filling operations. Since cement mixer trucks come in all sizes and shapes, with filling being accomplished anywhere from the front to the back of the truck depending on make and model, the problem of capturing dust and other dry particulate material has become more and more difficult.
In our U.S. Pat. No. 5,191,909 of Mar. 9, 1993, we have shown a particular hood for enclosing the filling end of the truck when the dry particulate material is being fed into the truck from the hoppers of a batch cement plant. In the aforesaid patent, we have disclosed a hood and flexible skirt arrangement for enclosing the end of the truck during the filling operation with an attached exhaust system for capturing the dust generated from within the enclosure and returning it to the appropriate hopper. The hood disclosed therein includes a pair of side curtains that can be opened to an extended position to allow entrance of a truck and enclosed about the truck to closely drape about and enclose the filling chute area of the truck so as to capture substantially all the dust created by the filling operation. This extendable clam shell type of enclosure has proved to be an improvement allowing easier alignment of the mixer truck with the filling chute while still substantially enclosing the truck during filling operation so as to capture and remove the environmentally damaging dust and particulate material.
While this disclosed construction has proven to be an improvement over prior art devices, the swinging door end enclosure panels have been found in some situations to present a problem for truck drivers. The hood assembly of the present invention improves upon the device disclosed in the above-referenced U.S. patent by providing the hood assembly with end panels that automatically open and close when the side panels are, respectively, extended and retracted.
The hood assembly is further improved by the present invention by providing adjustable features that allow proper operation at installation sites having space limitations.